If you are writing or studying, it makes much difference where the light comes from. People use 1and pens every day. They have to be very careful about the way of the light because the light shines on their work.
Every 2 gets its light either from daylight 3 the window 4 from the lamps or electricity, 5no matter what kind of light it is, the way it shines towards our books or work is very important to the eyes.
Take a book and sit with your 6 toward the window, and try to read. Your shadow(影子) falls all over the page and makes it 7 for your eyes as if you were in a 8 room.
Now turn around and face the window. The page is 9 shadow again, while the bright light is in your eyes.
Try sitting with your 10side toward the window. This is very good for 11 , but if you were writing, the shadow 12 fall across the page and bother you 13 .
There is another way – sit 14 your left side to the window. Now everything is perfect for writing as well.
Whatever kind of light is in the room, the rule about the right way to sit is 15 the same.
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